[vcloud] Remove helpless helper

Looks like this class is used to override Fog::Connection in testing
probably by manually tweaking the "false"

Since I'm deprecating Fog::Connection it's not worth keeping track off.
[core] Replace Fog::Connection with stable version

Fog::Connection mixed in XML parsing via the `parser` argument which
wasn't much use for the majority of APIs using JSON.

This adds the deprecation warning and attempts to update providers to
the correct version of Connection that they need.

Either the cleaner `Fog::Core::Connection` or if reliant on the XML
parsing still `Fog::XML::SAXParserConnection`

The SAX parser will be moving to `fog/xml` fairly soon.
Merge pull request #2708 from fog/replace_fog_connection

[core] Replace Fog::Connection with stable version